The art relating to water soluble polymeric films recognizes the use of the films in packaging. The primary commercial use of such packets has been in household applications in which pre-measured quantities of detergent materials can be packaged in water-soluble films for ease of use. Soluble packaging can also eliminate problems concerned with dusting and human contact with dust which can cause chemical attack and/or irritation of human skin and eyes and can cause other problems upon ingestion or inhalation.
Widespread use of water soluble packets containing detergent compounds has been hampered by physical and chemical compatibility of film with water and detersive systems. Many films such as polyvinyl-pyrrolidone, polyethyloxazoline and polyvinyl alcohol films can react with or interact with active components of a detersive system. Such films are known to be sensitive to moisture, which can soften the film and reduce tensile strength. However, more importantly, many of the chemicals commonly used in detergent compositions can attack the film and cause failure in the package integrity and/or water solubility especially when stored or used in humid conditions.
Researchers have attempted to alleviate PVA degradation problems by altering the film itself. Yang, et al. U.S. Pat. No. 4,747,976 discloses films comprising copolymers of 90-100% hydrolyzed vinyl alcohol with a non-hydrolyzable anionic comonomer having a viscosity range of 4-35 cP that can be used for alkaline or borate compositions. Gueldenzopf, et al. U.S. Pat. No. 4,654,395 discloses an addition polymer of a water insoluble soft monomer, a water soluble anionic monomer and optionally a water soluble nonionic monomer and water insoluble hard monomer which is neutralized to at least about 75% and formed into a sheet which can form a packet for bleaching chemicals etc.
Other attempts have been directed to using insoluble coatings to passivate the film envelope contents as shown in Lyon, Japanese Patent No. 63-012467, which discloses the use of a detergent coated with a micro fine insoluble powder enclosed in individual packets made of a water soluble film. This approach has the inherent drawback of introducing into a cleaning composition insoluble powders which can form residue on the surface after cleaning.
Therefore, a completely water soluble cleaning product free of insoluble materials that form residue is needed which is compatible with soluble polymer films and can be used in a number of cleaning applications.